12 Bolt Truck Differential - The 1947 - Present Chevrolet & GMC Truck Message Board Network

aviatorskate · 08-31-2015, 08:16 AM

I took my rear diff. apart several years ago on my 70 C10. I now have a new rebuild kit for it. I want to replace all bearings and races. Can I use the same pinion shim and carrier shims all in the original places, with and new crush sleeve set to proper preload and call it good ? I dont have to tool to measure the pinion depth.

Craig

Tony · 08-31-2015, 09:05 AM

I have done it that way several times with no problems...Of course there can be problems.
You don't need a depth gauge although it makes things easier and faster than pulling the pinion bearing on and off several times to change shims...
Very important is pinion and carrier bearing preload. How to do it is available from the gear manufacturers and gear vendors websites

**Ironangel** · 08-31-2015, 09:52 AM

Short answer is "yes." With new bearings and races, things might get a little tight. Check your wear pattern and as long as it appears to wear in the center of the coast side (if your reusing the existing gears) you should be alright. Like Tony indicated, I would check pinon preload with an inch pound torque wrench and backlash with a dial indicator...OEM pinion shim depth is .030" or close to that. Pinion preload is 13-15 (inch lbs) new, and 6-7 (inch lbs) used, and .006"-.010" (thousandths) backlash...Whats critical is maintaining some, but not to much backlash, and not going to far with that pinion bearing preload (crushing the sleeve to far)

~Ghostrider~

leftybass209 · 08-31-2015, 06:32 PM

In theory, yes it may work.

Since the shims will get it close, there would be minimal chance of the pinion walking into the carrier, but that is still a possibility.

You can try it and see where it gets you, as the crush sleeve isn't expensive, and most all issues will cause minimal to no damage if driven at slow to moderate speeds while you try and figure out if it's done correctly.

Mike C · 08-31-2015, 07:39 PM

If all you are doing is bearings and races, yes this should work just perfectly. I've done many this way with no issues. Like anything else, never say never, but bearings are such high tolerance items it should be back to whatever it was set at originally if you keep all the shims in the same position.

Make sure and mark the caps and the cast iron side shims and put them back on their appropriate positions and orientations.

**Ironangel** · 08-31-2015, 11:37 PM

Quote:

Originally Posted by Mike C

Make sure and mark the caps and the cast iron side shims and put them back on their appropriate positions and orientations.

<--<< What he said!

aviatorskate · 09-01-2015, 09:55 PM

Thanks everyone !

Craig

toolboxchev · 09-02-2015, 12:10 AM

I did it, no specs done, over 90 k now no real issues.

It can be tricky, though, but not that bad.

08-31-2015, 08:16 AM	#1
aviatorskate Registered User Join Date: May 2015 Location: Texas Posts: 18	12 Bolt Truck Differential I took my rear diff. apart several years ago on my 70 C10. I now have a new rebuild kit for it. I want to replace all bearings and races. Can I use the same pinion shim and carrier shims all in the original places, with and new crush sleeve set to proper preload and call it good ? I dont have to tool to measure the pinion depth. Craig

08-31-2015, 09:05 AM	#2
Tony Registered User Join Date: Sep 2001 Location: Ontario New Yak Posts: 843	Re: 12 Bolt Truck Differential I have done it that way several times with no problems...Of course there can be problems. You don't need a depth gauge although it makes things easier and faster than pulling the pinion bearing on and off several times to change shims... Very important is pinion and carrier bearing preload. How to do it is available from the gear manufacturers and gear vendors websites

08-31-2015, 09:52 AM	#3
Ironangel Senior Member Join Date: Feb 2010 Location: Falls City, Nebraska "100 Miles From Nowhere" Posts: 2,219	Re: 12 Bolt Truck Differential Short answer is "yes." With new bearings and races, things might get a little tight. Check your wear pattern and as long as it appears to wear in the center of the coast side (if your reusing the existing gears) you should be alright. Like Tony indicated, I would check pinon preload with an inch pound torque wrench and backlash with a dial indicator...OEM pinion shim depth is .030" or close to that. Pinion preload is 13-15 (inch lbs) new, and 6-7 (inch lbs) used, and .006"-.010" (thousandths) backlash...Whats critical is maintaining some, but not to much backlash, and not going to far with that pinion bearing preload (crushing the sleeve to far) ~Ghostrider~ __________________ Michael of the clan Hill, "Two Seventy Two's" 71 1-ton Dually 350 4-Speed 71 C/50 Grain Truck, 350 Split-Axle 4-Speed 02 3/4 ton Express 14 Indian Chief Vintage 1952 Ford 8N, "Only Ford Allowed On The Property" "Be American, Buy American"

08-31-2015, 06:32 PM	#4
leftybass209 Registered User Join Date: Feb 2011 Location: Modesto, CA Posts: 2,189	Re: 12 Bolt Truck Differential In theory, yes it may work. Since the shims will get it close, there would be minimal chance of the pinion walking into the carrier, but that is still a possibility. You can try it and see where it gets you, as the crush sleeve isn't expensive, and most all issues will cause minimal to no damage if driven at slow to moderate speeds while you try and figure out if it's done correctly.

08-31-2015, 07:39 PM	#5
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,723	Re: 12 Bolt Truck Differential If all you are doing is bearings and races, yes this should work just perfectly. I've done many this way with no issues. Like anything else, never say never, but bearings are such high tolerance items it should be back to whatever it was set at originally if you keep all the shims in the same position. Make sure and mark the caps and the cast iron side shims and put them back on their appropriate positions and orientations. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

09-01-2015, 09:55 PM	#7
aviatorskate Registered User Join Date: May 2015 Location: Texas Posts: 18	Re: 12 Bolt Truck Differential Thanks everyone ! Craig

09-02-2015, 12:10 AM	#8
toolboxchev Registered User Join Date: Jul 2015 Location: 2nd left past the stump on a dirt road. Posts: 2,629	Re: 12 Bolt Truck Differential I did it, no specs done, over 90 k now no real issues. It can be tricky, though, but not that bad.



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